/*=========================================================================
 *
 *  Copyright UMC Utrecht and contributors
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *=========================================================================*/
/*=========================================================================
*
*  Copyright Insight Software Consortium
*
*  Licensed under the Apache License, Version 2.0 (the "License");
*  you may not use this file except in compliance with the License.
*  You may obtain a copy of the License at
*
*         http://www.apache.org/licenses/LICENSE-2.0.txt
*
*  Unless required by applicable law or agreed to in writing, software
*  distributed under the License is distributed on an "AS IS" BASIS,
*  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
*  See the License for the specific language governing permissions and
*  limitations under the License.
*
*=========================================================================*/
#ifndef __itkGPUDataManager_h
#define __itkGPUDataManager_h

#include "itkObject.h"
#include "itkDataObject.h"
#include "itkObjectFactory.h"
#include "itkOpenCLContext.h"
#include <mutex>

namespace itk
{
/** \class GPUDataManager
 * \brief GPU memory manager implemented using OpenCL. Required by GPUImage class.
 *
 * This class serves as a base class for GPU data container for GPUImage class,
 * which is similar to ImageBase class for Image class. However, all the image-related
 * meta data will be already stored in image class (parent of GPUImage), therefore
 * we did not name it GPUImageBase. Rather, this class is a GPU-specific data manager
 * that provides functionalities for CPU-GPU data synchronization and grafting GPU data.
 *
 * \note This file was taken from ITK 4.1.0.
 * It was modified by Denis P. Shamonin and Marius Staring.
 * Division of Image Processing,
 * Department of Radiology, Leiden, The Netherlands.
 * Added functionality is described in the Insight Journal paper:
 * http://hdl.handle.net/10380/3393
 *
 * \ingroup ITKGPUCommon
 */
class ITKOpenCL_EXPORT GPUDataManager : public Object   //DataObject//
{
  /** allow GPUKernelManager to access GPU buffer pointer */
  friend class OpenCLKernelManager;

public:
  ITK_DISALLOW_COPY_AND_ASSIGN(GPUDataManager);

  typedef GPUDataManager             Self;
  typedef Object                     Superclass;
  typedef SmartPointer< Self >       Pointer;
  typedef SmartPointer< const Self > ConstPointer;

  /** Method for creation through the object factory. */
  itkNewMacro( Self );

  /** Run-time type information (and related methods). */
  itkTypeMacro( GPUDataManager, Object );

  using MutexHolderType = std::lock_guard<std::mutex>;

  /** total buffer size in bytes */
  void SetBufferSize( unsigned int num );

  unsigned int GetBufferSize()
  {
    return m_BufferSize;
  }

  void SetBufferFlag( cl_mem_flags flags );

  void SetCPUBufferPointer( void * ptr );

  void SetCPUDirtyFlag( bool isDirty );

  void SetGPUDirtyFlag( bool isDirty );

  /** Make GPU up-to-date and mark CPU as dirty.
   * Call this function when you want to modify CPU data */
  void SetCPUBufferDirty();

  /** Make CPU up-to-date and mark GPU as dirty.
   * Call this function when you want to modify GPU data */
  void SetGPUBufferDirty();

  bool IsCPUBufferDirty()
  {
    return m_IsCPUBufferDirty;
  }

  bool IsGPUBufferDirty()
  {
    return m_IsGPUBufferDirty;
  }

  /** actual GPU->CPU memory copy takes place here */
  virtual void UpdateCPUBuffer();

  /** actual CPU->GPU memory copy takes place here */
  virtual void UpdateGPUBuffer();

  void Allocate();

  /** Synchronize CPU and GPU buffers (using dirty flags) */
  bool Update();

  /** Method for grafting the content of one GPUDataManager into another one */
  virtual void Graft( const GPUDataManager * data );

  /** Initialize GPUDataManager */
  virtual void Initialize();

  /** Get GPU buffer pointer */
  cl_mem * GetGPUBufferPointer();

  /** Get GPU buffer pointer */
  void * GetCPUBufferPointer();

  /** Make CPU buffer locked to avoid extra update from ITK pipeline. */
  void SetCPUBufferLock( const bool v ) { this->m_CPUBufferLock = v; }
  itkGetConstReferenceMacro( CPUBufferLock, bool );

  /** Make GPU buffer locked to avoid extra update from ITK pipeline. */
  void SetGPUBufferLock( const bool v ) { this->m_GPUBufferLock = v; }
  itkGetConstReferenceMacro( GPUBufferLock, bool );

protected:

  GPUDataManager();
  virtual ~GPUDataManager();
  virtual void PrintSelf( std::ostream & os, Indent indent ) const;

protected:

  unsigned int m_BufferSize; // # of bytes

  OpenCLContext * m_Context;

  /** buffer type */
  cl_mem_flags m_MemFlags;

  /** buffer pointers */
  cl_mem m_GPUBuffer;
  void * m_CPUBuffer;

  /** checks if buffer needs to be updated */
  bool m_IsGPUBufferDirty;
  bool m_IsCPUBufferDirty;

  /** extra safety flags */
  bool m_CPUBufferLock;
  bool m_GPUBufferLock;

  /** Mutex lock to prevent r/w hazard for multithreaded code */
  std::mutex m_Mutex;
};

} // namespace itk

#endif
